This invention relates to an air-conditioner having excellent characteristics in a sleep mode operation, and more particularly to an air-conditioner permitting, in a sleep mode operation, a person sleeping in a room within which an indoor unit is provided to sleep well and permitting him or her to wake up with a feeling of comfort.
Generally, an air-conditioner having air cooling and heating functions is operated in various operation modes such as a rapid operation mode, and an ordinary operation mode, etc. However, even either in a rapid operation mode or in an ordinary operation mode, when a person is sleeping in a room within which an indoor unit for an air-conditioner is provided, he or she is more sensitive to hot or cold air than when he or she is waking and active. Accordingly, it is required to preset a set temperature to a lower one at the time of heating and to a higher one at the time of cooling. Furthermore, a louver for adjusting the direction of blowing of hot or cold air is required to be set so that hot air blows in a downwards direction at the time of heating and cold air blows in an upwards direction.
For this reason, in conventional air-conditioners, a so-called quiet sleep mode was set in order that a person in a room can sleep well. The sleep mode at the time of cooling is set to preset a set temperature to be slightly high, thus allowing cold air to blow in a direction of the ceiling of a room. Furthermore, the sleep mode at the time of heating is set to gradually lower a set temperature with the lapse of time in order that a temperature of the entire room gradually lowers with time, and to allow hot air to blow in a direction of the floor of the room. The control of the direction of blowing of conditioned air (cold air or hot air) is conducted by adjusting the in the form of a plate provided on the front side of the indoor unit of the air-conditioner so that it is directed upwardly or downwardly.
This indoor unit is comprised of, as shown in FIG. 1A, a front panel 1 having an air blowing opening at the lower side thereof, a rear panel 2 fixed on a wall of the room, a heat exchanger 4 disposed between these panels 1 and 2, an overflow fan 5 rotationally driven by a fan motor 6, and a louver 7 fluctuated and driven by a louver motor 8. In order that conditioned air most suitable for a person in a room to be air-conditioned is provided, a blowoff temperature sensor 9a and an exchanger temperature sensor 9b are secured at the blowing opening 1a and the heat exchanger 4, respectively. The indoor unit 10 is constituted by the components of the panel 1 to the sensor 9.
Particularly in the case of the sleep mode at the time of heating in the sleep operation mode as shown in FIG. 1B, the direction of the louver 7 in the indoor unit 10 is set to the ceiling direction of the room as indicated by a thick arrow so that blowoff air blows in a lower direction. Accordingly, hot air within the room R will flow as indicated by the dotted arrows. Thus, the blowoff air blows, directly and continuously or intermittently during sleeping, around a person sleeping in the room R.
The operation of an air-conditioner provided with an indoor unit shown in FIGS. 1A and 1B is automatically controlled by a control system, e.g., a microcomputer, etc. Such an automatic control is carried out not only in the case of the operation in the sleep mode, but also in the case of a timer operation mode. In this timer operation mode, when time reaches a predetermined time set in advance, the air-conditioner automatically starTS operation irrespective of whether or not a person is present in the room R. Also in this timer operation mode, the direction of the louver 7 is set obliquely downward by an angle .theta. relative to the horizontal direction as shown in FIG. 1A, or is set substantially downward as shown in FIG. 1B. Thus, cold air which has not yet warmed is blown directly to a person who is going to wake up.
As just described above, the conventional air-conditioner has the problem that when a person in a room sleeps close to the floor during heating operation, i.e., in the sleep and/or timer operation mode at the time of heating, a person subject to delivery of conditioned air feels uncomfortable by a wind blowing off downward through the louver set downward.
Furthermore, in the timer operation mode at the time of heating, there is a possibility that conditioned air which has not been yet warmed may often blow onto a person close to the floor. This leads to the problem that a person in a room wakes up by the blowing of cold air at an operation start time set by a timer for a time of sleeping in the early morning. Because a person in a room ordinarily desires to wake up in a room sufficiently warmed, it is a matter of course that a scheduled hour of rising is later than the timer operation start time.
A further problem is that when warm air blows around a person present in a room at the time of heating, he or she feels that a relative humidity felt by the skin is lower than an actual one, i.e., air in a room is extraordinarily dry even though an absolute humidity in a room is fixed.